oberhellmann



14, 1955 T. A. OBERHELLMANN 2,734,686

ADJUSTABLE HAMMER MILL 3 Sheets-Sheet 1 Filed Nov. 12, 1952 1 I I #l 14, 1956 T. A. OBERHELLMANN 2,734,686

ADJUSTABLE HAMMER MILL 3 Sheets-Sheet 2 Filed Nov. 12, 1952 Feb. 14, 1956 -r. A. OBEJRHELLMANN 2,73 ,686

ADJUSTABLE HAMMER MILL 5 Sheets-Sheet 3 Filed Nov. 12, 1952 w OI 2,734,686 Ice Patented Feb. 14, 1956 ADJUSTABLE HAMMER MILL Theodore A. Oberhellmann, St. Louis, Mo., assignor to Hammermills, Incorporated, Chicago, IlL, a corporation of Missouri Application November 12, 1952, Serial No. 319,811

21 Claims. (Cl. 241--82) The invention relates generally to grinding machinery and, more particularly, to hammer mills which have a plurality of hammers rotating within a grinding cage including grinding plates and a screen through which the ground material is ejected. This application is a continuation-in-part of my co-pending application Serial No. 55,533, filed October 20, 1948, for Adjustable Hammer Mill, which application has been abandoned without prejudice in view of its being superseded by this present application.

One object is to accurately gradate and control the size of any ground substance by adjusting the grinding plates to and from the hammers, and by varying the size of the openings in the material discharge screen corresponding to the distance of the adjusted grinding plates from the hammers.

Another object is to provide a pair of adjustable grinding plates for forming one portion of the grinding cage, which interengage on confronting ends and are pipotally mounted on their remote ends.

Another object is to provide a material discharge screen including a plurality of rockable louver plates wherein the spaces between the plates may be uniformly varied.

A further object is to facilitate maintenance by providing a material discharge screen comprised of a plurality of rockable louver plates which are mounted for independent replacement.

Another object is to eliminate fire hazards by trapping foreign objects, such as pieces of metal, etc., heavier than the material being ground, before the objects enter the grinding cage for engagement by the hammers.

Other detail objects will be apparent to those skilled in the art from the following description and accompanying drawings, in which:

Figure 1 is a side view of a hammer mill, constructed according to the invention, with portions of the housing cut away to show the louver plates mounted within the grinding cage.

Figure 2 is in part an end view and in part a transverse vertical section taken approximately on the line 22 of Figure 1.

Figure 3 is a rear view of the exhaust fan and discharge chute associated with the device.

Figure 4 is a detail vertical section of the louver plates and adjusting lever shown in Figure 2 and drawn to enlarged scale.

Figure 5 is a detail vertical section taken approximately on the line 5--5 of Figure 4.

Figure 6 is an end elevation of a hammer mill constructed according to the invention and embodying another form of discharge screen.

Figure 7 is a detail vertical transverse section taken on the line 7-7 of Figure 6.

Figure 8 is a detail vertical transverse section taken on the line 8--8 of Figure 6.

Figure 9 is a detail horizontal section taken on the line 9-7-9 of Figure 6.

The hammer mill includes a housing 1 having front and rear walls 2, 3, end walls 4, 5, and top and bottom walls 6, 7. Top wall 6 includes a hinged cover 8 for access into the interior of housing 1. An inclined material inlet chute 9 substantially the same width as housing 1 extends through front wall 2 and opens at its lower end into a substantially cylindrical grinding cage 10 within housing 1.

The upper part of the grinding cage includes a pair of grinding plates 11, 12, disposed edge to edge circumferentially of the cage and swingingly mounted at the lower remote ends on pivots 13, 14, respectively, on housing end walls 4, 5. The upper adjacent ends of the grinding plates may be swung about pivots 13, 14 by a lever 15 pivoted to housing end wall 5 by a pin 16 and connected by a link 17 to grinding plate 12. An extension 18 on grinding plate 12 is received in a recess 19 in the inner face of grinding plate 11 so that both grinding plates 11, 12 interengage and move together in response to movement of lever 15.

Lever 15 is clamped in adjusted position by a bolt 20 in a curved slotted bracket 21 rigid with housing 1. Also grinding plates 11, 12 may be locked in adjusted position by bolts 22 received in slots 23 in housing end walls 4, 5. Lever 15 and bolts 22 are assembled from outside housing 1 and the grinding plates may be adjusted while the machine is operating.

The lower part of grinding cage 10 includes a discharge screen 24 comprising a plurality of louver plates 25 extending between end walls 4, 5 and mounted by fixed pivots 26 on end walls 4, 5. Similar pivots 26a near the outer edge of each plate 25 are slidably socketed in slots 27a in shallow arcuate segments 27 sliding on tracks 28 on end walls 4, 5. Movement of segments 27 varies the inclination of the louver plates and the spaces between their inner ends.

A bell crank including arms 29, 31, is rigid with an elongated rod 30 rotatable in housing end walls 4, 5. Arm 29 is mounted exteriorly of the housing adjacent end wall 5 and arm 31 is mounted adjacent to and on the opposite side of end wall 5. Another arm 31 rigid with rod 30 is positioned within the housing adjacent end wall 4 and both arms 31 are connected by levers 32 to segments 27. The louver plates may be adjusted to vary the space between their inner ends by swinging arms 29, 31 and links 32 between the positions indicated in solid lines in dot-dash lines in Figure 2. Arm 29 may be clamped after adjustment to a slotted curved bracket 33 by a bolt 33a.

A plurality of hammers 34 are mounted on pillow blocks 35 secured to a shaft 36 extending through apertures in end walls 4, 5 'and journaled in bearings 37 on pedestals 38 mounted on extensions 39, 40 on housing 1. An electric motor 41 on extension 40 is coupled at 41a to shaft 36 and revolves hammers 34 within the grinding cage.

The size of the finished product may be varied from /2" to 300 mesh by adjusting grinding plates 11, 12 relative to hammers 34, and by correspondingly changing the angular setting of louver plates 25. If the grinding plates are relatively close to the hammers, the material will be ground finer than when the space between the grinding plates and hammers is increased. When the louver plates are positioned substantially radially of the grinding cage, as shown in solid lines in Figure 2, relatively coarse particles will pass between the plates into the lower portion of housing 1. When the louver plates 25 are inclined to radii of the grinding cage, as shown in dot-dash lines in Figure 2, screen 24 will pass only relatively fine particles. Because of the construction of grinding plates 11, 12 and the louver plate screen 24 and by the convenient location of the control means therefor, a relatively unskilled operator can etfectively and quickly make any indicated adjustment so that the hammer mill can be readily adapted for any product.

For enhancing the quality of the ground product, the hammermill is provided with means for controlling the flow of air therethrough which includes an electric motor 42 for rotation of an exhaust fan 43 within a housing 44 connected by a conduit 45 within the lower portion of housing 1. The axis of conduit 45 extends transversely of the axis of the cage and draws the air fairly uniformly through the entire length of the cage. A discharge conduit D leads upwardly from housing 44 to any desired point.

A pair of adjustable air intakes 46 extends substantially the entire width of front Wall 2 below grinding cage 10 and cooperate with fan 43 to create an air stream throughout substantially the entire width of the hammer mill. Covers 47 are slidable on front wall 2 between pairs of guide elements 48. Covers 4'7 may be adjusted to open intakes 46 any desired amount and may be held in adjusted position by tightening screws 4? received in slots 50 in covers 47.

The length of time the material remains in cage 10 and is subjected to the hammer action may be varied by adjusting covers 47, thereby controlling the passage of the air stream through the cage. When covers 47 close intakes 46, fan 43 will draw air into cage 10 through material inlet chute 9 and will create a strong draft directly through screen 24 tending to accelerate the passage of the material through the machine so that the grinding will be a minimum, that is, the material will not be subjected to repeated hammering to the extent it would be if the material were discharged by gravity alone. By opening intakes 46 varying degrees, the force of the draft through cage ill will decrease and material will remain in the cage longer and be reduced to smaller size.

The lower end of material inlet chute is apertured at '1 and opens into a chamber 52 in housing 1. A pan 62a forms the bottom of chamber 52. An adjustable air intake 53 extends substantially the entire width of front wall'2 and opens into chamber 52. A cover 54, similar to covers 47 previously described, may be adjusted to open intake 53 any desired amount. Foreign objects, such as pieces of metal, etc., heavier than the material being ground, fall through aperture 51 into pan 52a. The lighter when grinding such substances as shelled corn, oats, clays,

and fullers earth. Itis especially desirable to produce a granulated corn without powder. Therefore, when grinding corn, air intakes 46 are completely closed, so that hammer action on the corn is a minimum. Oats are preferably ground very fine without slivers, and adjustable air intakes 46 are opened substantially so that hammer action on the oats may be repeated.

The machine may be used to grind any substance, including grains, chemicals, gypsum, etc. and the size of the ground substance may be accurately controlled by adjusting the grinding plates relative to the hammers, and by correspondingly varying the angle of the louver plates. By the further operation of properly controlling the air stream for the particular material being ground, the end product will be of increased quality. By having inlet chute 9 and air intake 46 and outlet 45 extend substantially the entire width of the housing, air currents are provided throughout the entire width of the hammer mill and the hammers and louver plates are utilized to their maximum capacity and thus wear is distributed on the hammers and louver plates substantially uniformly.

Fire hazards in the machine are eliminated because foreign objects, likely to create sparks when engaged by the hammers, are trapped before they enter the grinding cage.

Preferably segments 28 are made in a plurality of sections connected by links 280 to facilitate assembly and replacement but the successive sections function as a single unit.

While the grinding plates are shown at the top of the cage and the louver plates at the bottom of the cage, these positions may be reversed and the discharge effected solely by the air stream independently of gravity if such an arrangement is preferred.

Figures 6, 7 and 8 show another form of discharge screen, generally indicated at 66, for use with a hammer mill of the type above described. Screen comprises a plurality of louver plates 61 each having a recess 62 in the upper half of its end face for receiving a dog point set screw 63 threaded into the housing end wall 5, whereby the plate is rockable about a stationary pivot on the end wall. Below recess 62 each louver plate 61 is recessed to form an open ended slot or groove 64 for freely receiving the pin-forming end of a set screw 65 threaded into an arcuate plate segment or semi-ring-like rigid member 66 suidable on the exterior face of the housing end Wall 5 substantially concentrically with the grinding cage. Segments 66 are slidable through an are by means of an in- :ardly projecting arcuate runner portion 67 disposed within a track 65 formed in end wall 5, with the limit of such movement being determined by abutment of studs 69 mounted in end wall 5 against the ends of arcuate slots 76 provided in segments 66.

Segment 66 is pivotally connected to one end of a rod 71 having its other end pivoted to one arm 72 of a bell crank 73 fixed on a pin 74 journaled at its ends in the housing end wall and in a bracket 75 mounted on the end wall. The other arm 76, of each bell crank, projects through an opening in the associated mounting bracket 75 for engagement by bolts 77 to slotted, curved brackets 78 similar in all respects to brackets 33 above described.

By operation of hell cranks 73, segments 66 maybe slidably moved along arcuate tracks 68 causing pins 65 to rock respective louver plates 61 on their pivots 63 to uniformly vary the intervening spaces in correspondence to the selected adjustment of grinding plates 11, 12.

In order to replace a louver plate 61 it is merely necessary to loosen or back ofi screws 63 and 65 to permit a plate 61 to be lifted from the screen, with reverse operation for installing another plate. Thus by unique construction, louver plates 61 may be independ ently removed and installed without the necessity of laborious disassembly and reassembly of other portions of the hammer mill.

It should be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the hammer mill may be made and substituted for those herein shown and described without departing from the nature and principle of the present invention.

What is claimed is:

1. In a hammer mill, a rotatable hammer, an adjustable cylindrical grinding cage, comprising a pair of arcuate grinding plates defining the upper portion of the cage, said plates being interengaged on confronting ends and being pivotally mounted on their remote or outer ends on said housing for radial swingable movement for regulating the grinding space between them and the hammer, and an arcuate structure defining the lower portion of said cage and comprisinga plurality of rockable, spaced louvers, and means for rocking said louvers whereby the spaces therebetween may be varied uniformly to correspond to the radial distance between the hammer and said plates.

2. In a hammer mill, a rotatable hammer, an. adjustable cylindrical grinding cage, comprising apair of arcuate grinding plates defining the upper portion of the cage, said plates being interengaged on confronting ends and being pivotally mounted on their remote or outer ends on said housing for radial 'swingable movement for for individual rockable movement, a member slidably mounted on an end wall and engageable with the louvers individually, and means exteriorly of the cage for moving said member whereby said louvers may be rocked for uniformly varying the spaces therebetween in predetermined correspondence to the radial distance between the hammer and grinding plates.

3. In a hammer mill, an adjustable cylindrical grinding cage comprising a pair of arcuate grinding plates defining the upper portion of the cage, said plates being interengaged on confronting ends and being pivotally mounted on their remote or outer ends on said housing for radial swingable movement for regulating the grinding space in the upper portion of the cage whereby, when increased fineness of grinding is desired, said plates will be swung to decrease the normal radius of the cage, lever means connected to at least one of said plates for swinging same into desired position and to efifect mutual swinging of the other plate through the interengagement, and a screen member defining the lower portion of said cage and comprising a plurality of rockable, spaced louvers with narrow edges and relatively wide flat side faces disposed with their side faces normally in radial relation to said cage, and means for rocking said louvers uniformly with their side faces out of radial relation with said cage for varying the spaces therebetween in correspondence to the radial disposition of said grinding plates.

4. In a hammer mill, a housing, a substantially cylindrical grinding cage in said housing including a pair of adjacent arcuate grinding plates defining portions of said.

cage, said grinding plates being pivotally mounted at their outer ends on said housing and being interengaged at their inner ends, and means engaged to one of said plates for swinging same and to effect mutual swinging of the other plate through the interengagement for moving said plates substantially equally angularly.

5. In a hammer mill, a housing, a substantially cylindrical grinding cage in said housing including a pair of adjacent arcuate grinding plates as described in claim 4 wherein the means for effecting swinging on the plates is located on the exterior of the housing.

6. In a hammer mill having a housing, a substantially cylindrical grinding cage in said housing including a pair of curved grinding plates in edge to edge relation defining adjacent portions of said cage, rotating hammers in the cages, said plates, on their remote outer edges, being pivotally mounted on said housing for radial movement of their confronting edges inwardly and outwardly relative to the hammer to control the eifective grinding space of the cage whereby requisite fineness of grinding may be provided for the particular material being ground,

and lever means provided on said housing and opera tively engaged to at least one of said plates for moving same into selected position, the confronting edges of the plates being interengaged so that movement of one plate by said lever means also moves the other plate.

7. In a hammer mill, a housing, a substantially cylindrical grinding cage in said housing including a pair of curved grinding plates disposed edge to edge circumferentially of the cage and forming approximately the upper half of said grinding cage, said grinding plates being pivoted at their lower remote edges to said housing, the adjacent upper edges of said grinding plate interengaging with one another, said plates being swingable about their pivoted ends inwardly and outwardly of said cage, and a lever pivoted to said housing and accessible exteriorly thereof and connected to at least one of said grinding plates to provide for swinging same and to effect 6 mutual swinging through the interengag'ement of the other of said plates.

8. Structure as described in claim 7, including means for locking said lever and additional elements for locking said grin-ding plates in adjusted position.

9. In a hammer mill, a substantially cylindrical grinding cage including an end wall, a rotating hammer in said cage, a discharge screen forming one side of the cylindrical cage, a rigid arcuate plate substantially concentric with the axis of said hammer and slidable on said end wall about said axis, said plate having a plurality of slots inclined to the radius of its arc, said discharge screen including a plurality of elongated fiat louvers corresponding in number to said slots and extending lengthwise of the cage with their side faces disposed generally radially of said axis, a pivot connecting the end of each louver to the end wall, a pin on the lower edge of each louver being slidable in a corresponding slot in said plate, and means for sliding said plate on said wall to tilt said louvers on their pivots.

10. In a hammer mill, a substantially cylindrical grinding cage including an end wall, a rotating hammer in said cage, a discharge screen as described in claim 9 wherein the means for sliding said arcuate plate segment includes a lever located exteriorly of the hammer mill.

11. In a hammer mill, a substantially cylindrical grinding cage including an end wall, a rotating hammer in said cage, a discharge screen as described in claim 9 wherein the distance between the pivot and pin associated with each louver plate is constant.

12. In a hammer mill having a cylindrical grinding cage including end walls, a discharge screen defining the lower portion of said cage and comprising a plurality of spaced louvers extending between the end walls, said louvers having first pivot pins projecting from their upper end margins for engagement with said end walls for rockable movement thereabout, arcuate plate segments mounted on the inner face of the end walls in substantial concentricity with said cage, said segments being mounted for slidable movement circumferentially of said cage, said segments having spaced socket-forming slots on their inwardly presented faces in register with the louvers, said'louvers further including second pivot pins for reception with said slots, and lever means exteriorly of the hammer mill for moving said segments whereby said louvers may-be rocked on said first pivot pins.

13. In a hammer mill having a grinding cage including end walls, a discharge screen defining the lower portion of said cage and comprising a plurality of spaced louver plates extending between the end walls, said louver plates being pivotally engaged to said end walls in their upper end portions for rockable movement, arcuate plate segment members mounted on the exterior faces of the end walls for slidable movement, a plurality of pin members engaged to said plate segment members for projection through the end walls, each louver plate having a walled end slot for freely receiving a pin member, and lever means for moving said plate segments for effecting engagement between said pin members and a wall of the slot of the associated louver plates to cause the latter to be rocked.

14. In a hammer mill having a grinding cage including end walls, a discharge screen as described in" claim 13 wherein the distance between the point of pivotal engagement of each louver and the pin member received in the slot thereof is constant whereby upon rocking of the louver plates the intervening spaces will be uniformly varied.

15. In a hammer mill having a grinding cage including. end walls, a discharge screen defining the lower portion of said cage and comprising a plurality of spaced louver plates extending between the end walls, said louver plates each having a recess in their upper end margin, pivot pins mounted in said end walls for reception within said recesses whereby said louver plates may be rocked,

arcuate plate segment members mounted on the exterior faces of said end walls and having arcuate runner portions disposed within tracks formed in the end walls whereby said plate segment members may be slidably moved, a plurality of pin members engaged in said plate segment members for projection through the runner portions and into the interior of the cage, each louver plate having a walled end slot for freely receiving one of the pin members, and lever means for moving said plate segments for effecting engagement between said pin members and one wall of the slot of the associated louver plates to cause the latter to be rocked.

16. In a hammer mill having a grinding cage including end walls, a discharge screen as described in claim wherein the distance between the pivot pin and pin member associated with each louver plate is constant so that upon rocking of the latter through movement of the plate segments the intervening spaces between the louver plates will be uniformly varied.

17. In a hammer mill, a housing, a grinding cage in said housing, a substantially straight line, downwardly inclined material inlet chute discharging at its lower end into said cage, a chamber immediately below said chute, an aperture in the bottom wall of said chute for opening into said chamber, an air intake in the side of said chamber, and a fan disposed at the opposite side of the hammer mill housing from said air intake, said fan providing for the passage of an air stream through said chamber and apertured into said gr'mding cage, said chute, chamber, and aperture being arranged so that material heavier than the material to be ground falls by gravity through said aperture and is trapped in said chamber and material to be ground is carried by said air stream into said cage.

18. In a hammer mill, a housing, a grinding cage in said housing, a rotating hammer in said cage, a substantially straight line, downwardly inclined material inlet chute discharging at its lower end into said cage, a chamber immediately below said chute, an aperture in the bottom wall of said chute for opening into said chamber, an air intake in said chamber, and a fan disposed at the opposite side of the hammer mill housing from said air intake, said fan providing for the passage of an air stream through said chamber and aperture into said grindingcage, said aperture being spaced from the lower discharge end of said chute so that material heavier than the material being ground falls by gravity through said aperture and is trapped in said chamber and avoids contact with said hammers and lighter material in said chute to be ground is propelled by said air stream into said cage for grinding action by said hammers.

19. In a hammer mill, a housing, a grinding cage in said housing and including a grinding plate and a discharge screen, a substantially straight line, downwardly inclined material inlet chute discharging at its lower end into said cage, a chamber immediately below said chute, an aperture in the bottom wall of said chute for opening into said chamber, an adjustable air intake in said chamber, an adjustable air intake opening into said housing exteriorly of said grinding cage, and a suction fan disposed at the opposite side of the housing from the housing'adjustable air intake opening providing for the passage of air streams into said chamber and providing for the passage of an air stream into said housing intake across the lower portion of said discharge stream, the relative intensities of said air streams being determined by the adjustment of said housing and chamber air intakes.

20; Av discharge screen. unit. in the form of a cylindrical section to. form a portion of the cage of a hammer millcomprising a plurality of louver plates, each having wide side faces, disposed substantially radially of the section, and having relatively narrow edges disposed in a semi-cylindrical line: about the axis of the section, an individual pivot mounting for each end of each of said louver plates having an axis extending longitudinally of the plate, an arcuate plate segment slidable upon the cage about a center corresponding to the center of said cylindrical section provided. with elements engageable with said louver plates and slidable therewith circumferentially of said section to swing said louver plates about said pivots from a position in which their wide side faces are disposed radially to positions inclined thereto, thereby varying the spaces between the plates circumferentially of the section without substantial variation in the spacing of the edges of the plates relative to the axis of the section.

21. A discharge screen for the grinding cage of a hammer mill including a substantially semi-cylindrical body formed of a plurality of louvers positioned side by side, each having opposite wide side faces and opposite narrow edges, a pivot mounting for each end of each of said louvers, a track-like element extending circumferentially of said body, and a semi-ring-like rigid member having angularly slidable engagement with each of said louvers and movable on said track-like element circumferentially of said body to swing said louvers about said pivots between positions in which their wide side faces extend substantially radially of said body into positions inclined thereto, thereby altering the spacing between the wide side faces of said louvers.

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